The genomic organization,promoter position and expression profile of the mouse MRG15 gene

MORF4 (mortality factor on chromosome 4) and the novel related MRG (MORF4-related gene) gene family were identified when MORF4 was shown to induce senescence in a subset of tumor cell lines. The gene on chromosome 15 (MRG15) has high similarity to Drosophila MSL3, which is a component of the dosage compensation complex. MRG15 also has a chromodomain and may therefore function as a chromatin remodeling factor in a complex(es) involving a histone acetyltransferase, similar to MSL3. To complement our studies on human MRG15, we cloned and characterized the mouse MRG15 gene. Mouse MRG15 is expressed ubiquitously in adult tissues and at various embryonic stages, and expression in adult testis is higher than in other tissues. MRG15-b, which is an alternatively spliced form of MRG15-a and has a 39-amino-acid insertion in the chromodomain, is also expressed in all mouse tissues examined and localizes to the nucleus of cells. It is possible that MRG15-b may lack the function of the chromodomain because of the additional amino acids and could potentially be the equivalent of the human MORF4 in the mouse. The mouse MRG15 gene is composed of twelve exons and spans over 24 kb DNA. Using luciferase constructs we have determined that there is a functional promoter sequence 1.8 kb upstream of the ATG start codon. This region contains no TATA box but has GC-rich regions, consistent with the ubiquitous expression we have observed.     

Nuclear organisation and gene expression

The development of increasingly sophisticated tools to track chromosomes and proteins in living cells offers the possibility of visualising gene regulation in the nucleus with minimal distortion. This, in conjunction with powerful genetic approaches available in yeast, is beginning to allow functional definition of nuclear "compartments".     

Root organization and gene expression patterns

New tools of microscopy, molecular biology, and genetics aremaking it possible for biologists to study roots with new vigour.Such investigations have enabled plant biologists to noticethe symmetry, pattern, and simplicity of root structures sothat there is now an exciting rebirth in the study of roots.The literature of root biology, development and structure isvast. In this short review we will concentrate on describingour notion of how roots are organized structurally, and thendiscuss what is known about tissue- and zone-specific gene expressionin roots. Key words: Root apex, root anatomy, root development, gene expression     

核基质与基因表达调控研究进展

核基质是细胞核内由一群复杂多样的非组蛋白构成的纤维网状结构。核基质蛋白具有明显的组织细胞特异性及肿瘤相关性。它作为细胞核的支架结构,在ＤＮＡ的复制、转录、ＲＮＡ加工修饰等重要的细胞内事件中起着支持和调节作用,并通过转录调节因子、核基质结合元件以及核基质蛋白与ＤＮＡ的相互作用等多种途径参与基因的表达调控     

The myrosinase gene family in Arabidopsis thaliana: gene organization,expression and evolution

Myrosinase (thioglucoside glucohydrolase, EC 3.2.3.1.) is in Brassicaceae species such as Brassica napus and Sinapis alba encoded by two differentially expressed gene families, MA and MB, consisting of about 4 and 10 genes, respectively. Southern blot analysis showed that Arabidopsis thaliana contains three myrosinase genes. These genes were isolated from a genomic library and two of them, TGG1 and TGG2, were sequenced. They were found to be located in an inverted mode with their 3 ends 4.4 kb apart. Their organization was highly conserved with 12 exons and 11 short introns. Comparison of nucleotide sequences of TGG1 and TGG2 exons revealed an overall 75% similarity. In contrast, the overall nucleotide sequence similarity in introns was only 42%. In intron 1 the unusual 5 splice border GC was used. Phylogenetic analyses using both distance matrix and parsimony programs suggested that the Arabidopsis genes could not be grouped with either MA or MB genes. Consequently, these two gene families arose only after Arabidopsis had diverged from the other Brassicaceae species. In situ hybridization experiments showed that TGG1 and TGG2 expressing cells are present in leaf, sepal, petal, and gynoecium. In developing seeds, a few cells reacting with the TGG1 probe, but not with the TGG2 probe, were found indicating a partly different expression of these genes.     

The organization and expression of histone gene families

The reiteration frequency of the genes that encode the structural proteins of the mammalian ribosome was studied with a set of cloned cDNA probes containing several different mouse r-protein mRNA sequences. Results from a reassociation kinetics analysis, Southern blotting experiments and gene cloning studies collectively indicate that each individual r-protein species is represented by multiple genes in mammals. Among the examples studied, the multiplicity of mouse r-protein genes varied from about 7 to 20, a striking contrast to the low copy numbers observed in less evolutionarily advanced eucaryotes. The multiplicity of individual r-protein genes in humans and rodents is similar.